The present invention relates generally to eggs and, more particularly, to methods and apparatus for processing eggs.
Discrimination between poultry eggs on the basis of some observable quality is a well-known and long-used practice in the poultry industry. xe2x80x9cCandlingxe2x80x9d is a common name for one such technique, a term which has its roots in the original practice of inspecting an egg using the light from a candle. As is known to those familiar with eggs, although egg shells appear opaque under most lighting conditions, they are in reality somewhat translucent, and when placed in front of direct light, the contents thereof can be observed.
An egg may be a xe2x80x9clivexe2x80x9d egg, meaning that it has a viable embryo. FIG. 1A illustrates a live poultry egg 1 at about day one of incubation. FIG. 1B illustrates the live egg 1 at about day eleven of incubation. The egg 1 has a somewhat narrow end in the vicinity represented at 1a as well as an oppositely disposed broadened end portion in the vicinity shown at 1b. In FIG. 1A, an embryo 2 is represented atop the yolk 3. The egg 1 contains an air cell 4 adjacent the broadened end 1b. As illustrated in FIG. 1B, the wings 5, legs 6, and beak 7 of a baby chick have developed.
An egg may be a xe2x80x9cclearxe2x80x9d or xe2x80x9cinfertilexe2x80x9d egg, meaning that it does not have an embryo. More particularly, a xe2x80x9cclearxe2x80x9d egg is an infertile egg that has not rotted. An egg may be an xe2x80x9cearly deadxe2x80x9d egg, meaning that it has an embryo which died at about one to five days old. An egg may be a xe2x80x9cmid-deadxe2x80x9d egg, meaning that it has an embryo which died at about five to fifteen days old. An egg may be a xe2x80x9clate-deadxe2x80x9d egg, meaning that it has an embryo which died at about fifteen to eighteen days old.
An egg may be a xe2x80x9crottedxe2x80x9d egg, meaning that the egg includes a rotted infertile yolk (for example, as a result of a crack in the egg""s shell) or, alternatively, a rotted, dead embryo. While an xe2x80x9cearly deadxe2x80x9d, xe2x80x9cmid-deadxe2x80x9d or xe2x80x9clate-dead eggxe2x80x9d may be a rotted egg, those terms as used herein refer to such eggs which have not rotted. Clear, early-dead, mid-dead, late-dead, and rotted eggs may also be categorized as xe2x80x9cnon-livexe2x80x9d eggs because they do not include a living embryo.
Eggs which are to be hatched to live poultry are typically candled during embryonic development to identify clear, rotted, and dead eggs (collectively referred to herein as xe2x80x9cnon-live eggsxe2x80x9d). Non-live eggs are removed from incubation to increase available incubator space. In many instances it is desirable to introduce a substance, via in ovo injection, into a live egg prior to hatch. Injections of various substances into avain eggs are employed in the commercial poultry industry to decrease post-hatch mortality rates or increase the growth of the hatched bird. Similarly, the injection of virus into live eggs is utilized to propagate virus for use in preparing vaccines. Examples of substances that have been used for, or proposed for, in ovo injection include vaccines, antibodies and vitamins. Examples of in ovo treatment substances and methods of in ovo injection are described in U.S. Pat. No. 4,458,630 to Sharma et al., the contents of which are hereby incorporated by reference as if recited in full herein.
In ovo injections of substances typically occur by piercing an egg shell to create a hole therethrough (e.g., using a punch or drill), extending an injection needle through the hole and into the interior of the egg (and in some cases into the avain embryo contained therein), and injecting one or more treatment substances through the needle. An example of an injection device is disclosed in U.S. Pat. No. 4,681,063 to Hebrank; this device positions an egg and an injection needle in a fixed relationship to each other, and is designed for the high-speed automated injection of a polarity of eggs. The selected of both the site and time of injection treatment can also impact the effectiveness of the injected substance, as well as the mortality rate of the injected eggs or treated embryos. See, for example, U.S. Pat. No. 4,458,630 to Sharma et al., U.S. Pat. No. 4,681,063 to Hebrank, and U.S. Pat. No. 5,158,038 to Sheeks et al. U.S. Pat. No. 5,158,038 to Sheeks et al., U.S. Patents cited herein are hereby incorporated by reference herein in their entireties.
In commercial poultry production, only about 60% to 90% of commercial broiler eggs hatch. Eggs that do not hatch include eggs that were not fertilized, as well as fertilized eggs that have died. Infertile eggs may comprise from about 5% up to about 50% of all eggs in a set. Due to the number of non-live eggs encountered in commercial poultry production, the increasing use of automated methods for in ovo injection, and the cost of treatment substances, an automated method for identifying live eggs and selectively injecting only live eggs, is desirable.
There are other applications where it is important to be able to distinguish between live and nonlive eggs. One of these applications is the cultivation and harvesting of human flu vaccines via live eggs (referred to as xe2x80x9cvaccine production eggsxe2x80x9d). Human flu vaccine production is accomplished by injecting seed virus into a chicken egg at about day eleven of embryonic development (Day-11 egg), allowing the virus to grow for about two days, euthanizing the embryo by cooling the egg, and then harvesting the amniotic fluid from the egg. Typically, eggs are candled before injection of a seed virus to remove non-live eggs. Vaccine production eggs may be candled one or more days prior to injection of a seed virus therein. It is desirable to prevent seed vaccine from being wasted in non-live eggs and to eliminate costs associated with transporting and disposing of non-live eggs.
U.S. Pat. No. 3,616,262 to Coady et al. discloses a conveying apparatus for eggs that includes a candling station and an inoculation station. At the candling station, light is projected through the eggs and assessed by a human operator, who marks any eggs considered non-live. Non-live eggs are manually removed before the eggs are conveyed to the inoculating station.
U.S. Pat. Nos. 4,955,728 and 4,914,672, both to Hebrank, describe a candling apparatus that uses infrared detectors and the infrared radiation emitted from an egg to distinguish live from infertile eggs. U.S. Pat. No. 4,671,652 to van Asselt et al. describes a candling apparatus in which a plurality of light sources and corresponding light detectors are mounted in an array, and wherein eggs are passed on a flat between the light sources and the light detectors.
Unfortunately, conventional candling techniques may have somewhat limited accuracy, especially at high candling through-put speeds. Pulsed light opacity identification systems can operate at speeds equivalent to about 300,000 eggs per hour and successfully identify clear eggs from a stream of eggs. However, some eggs identified as being live will in fact be non-live (e.g., rotted eggs, mid and late dead eggs).
Thermal-based candling systems can detect rotted eggs in egg streams of up to 50,000 eggs per hour. In the candling method and apparatus described in U.S. Pat. No. 4,914,672 to Hebrank, for example, a thermal candling system measures the temperature of each egg from the bottom. The thermal candling system determines a threshold temperature. Eggs above the threshold temperature are deemed live and eggs below the threshold temperature are deemed non-live (which includes dead and clear eggs). Unfortunately, because of egg-to-egg thermal variations, thermal-based candling systems may misidentify live and non-live eggs.
FIG. 2 illustrates exemplary light value curves for live eggs and non-live eggs as measured via a light opacity candling system. Curve 10 is an upper end of a Gaussian-like cumulative distribution of light values for live eggs, and curve 12 is a lower end of a Gaussian-like cumulative distribution of light values for non-live eggs. The shaded area 14 represents a mixture of live eggs and non-live eggs in a stream of eggs because of overlapping light values. In other words, a live egg may have a light value, for example, of thirty (30), but a non-live egg may also have a light value of thirty (30). The candling system producing these light value curves cannot identify whether an egg having a light value within the range of the shaded area 14 is live or non-live.
Pulse detection methods are known that can detect live eggs with a high degree of accuracy. For example, Buddy by Avitronics (Truro, England) can reliably detect embryo heartbeats. Detection happens in about five to ten seconds for about 60% of eggs, with near 100% detection requiring 60 second sampling times. Unfortunately, the time required to detect a live egg is prohibitively slow for use in hatcheries where high through-put rates are required. For automated pulse detection to be a useful method of determining viable eggs, a much shorter processing time is needed to read hatchery volumes of eggs (typically several hundred thousand in six to eight hours).
A more recent development of pulse detection technology uses heartbeat or embryo motion to detect live eggs and can operate up to 500 eggs per hour per sensing device.
U.S. Pat. No. 5,173,737 to Mitchell describes a method of determining whether an egg contains a live embryo by directing light into an egg to stimulate embryo movement, and then measuring resulting embryo movement. Unfortunately, the Mitchell method may be time-consuming and may not accurately detect live embryos that do not move as a result of light stimulation.
In view of the above discussion, systems and methods of rapidly identifying live eggs within a stream of eggs with high accuracy, are provided. According to an embodiment of the present invention, a stream of presumably embryonated eggs are candled via a candling apparatus (light candling, thermal candling, etc.) and each candled egg is designated as being either live, non-live, or xe2x80x9cuncertainxe2x80x9d. Eggs designated as non-live and uncertain are removed from the stream. Each egg designated as uncertain is xe2x80x9crecandledxe2x80x9d at a separate station via an additional candling procedure in order to definitively determine if the xe2x80x9cuncertainxe2x80x9d egg is live or non-live.
According to an embodiment of the present invention, recandling may include embryo pulse detection and/or embryo motion detection. According to another embodiment of the present invention, recandling may include xe2x80x9chand candlingxe2x80x9d wherein a person manually candles an egg via a light source to determine if the egg is live or non-live. As is understood by those skilled in the art, hand candling typically takes place in a dark room. A light source is held to each egg. If the egg is completely yellow with no dark areas or visible veins then it is classified as xe2x80x98clearxe2x80x99 (infertile or very early dead). Indistinct dark areas or a cloudy or mottled appearance indicates a dead egg. A greenish hued color indicates a likely rotten egg. Live eggs have clearly visible red veins, a distinct air cell circle at the top (blunt) end of the egg and an identifiable dark embryonic area. Movement may be seen. In addition, human candlers pick out cracked eggs, upside down embryos and eggs with side air cells.
According to another embodiment of the present invention, recandling may include generating a light intensity spectrum of light passing through an egg and comparing the spectrum with a spectrum associated with a live egg.
Uncertain eggs identified as being live via recandling are returned to the egg stream such that the stream contains only live eggs. The live eggs may then be subjected to further processing, such as in ovo injection of a vaccination or other inoculation or virus injection. The uncertain eggs determined to be non-live via recandling are removed and are either discarded or used for other purposes.